Lord Coe said on Wednesday that he did not believe the swimmer Michael Phelps should be considered the greatest ever Olympian after he won his 19th medal in the pool. Speaking the morning after the American won his 15th gold medal of London 2012 at the Aquatics Centre in the 4x200m freestyle relay, Coe listed several athletes who could lay claim to the title as the greatest above the 27-year-old from Balitimore.

"Self-evidently, by his medal tally, he is the most successful but from a personal point of view I don't think he is the greatest," he said.

Asked who is, he said: "I have no idea. I could throw out a whole series of names. Steve Redgrave, domestically Daley Thompson. If I wanted to go back a few generations I think what Jesse Owens did in 1936 was unbelievable, Nadia Comaneci. It is the global pub game."

He initially appeared to put himself in the frame, albeit jokingly, when he said "modesty prevents me, but …"

The chairman of the London organising committee also weighed into the controversy around the outstanding performance of the 16-year-old Chinese swimmer Ye Shiwen.

"It is not the first time teenagers have broken world records or won Olympic titles," he said, following doubts raised by USA coach, John Leonard, when she recorded the third quickest time in history to win the 200m individual medley gold. "You have got to be very careful when you suddenly assume that a massive and unexpected breakthrough in an event is based on anything other than great coaching, extraordinary talent and all the other things. I remember in my late teens taking four and a half seconds off my 800m personal best. It really is not that unthinkable.

"My instinct is always to give the benefit of the doubt to the competitor until proved otherwise. My instinct is to celebrate what was an extraordinary performance."